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cgroup: fix harmless bugs in cgroup_load_subsys() fail path and cgroup_unload_subsys()

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* If idr init fails, cgroup_load_subsys() cleared dummytop->subsys[]
  before calilng ->destroy() making CSS inaccessible to the callback,
  and didn't unlink ss->sibling.  As no modular controller uses
  ->use_id, this doesn't cause any actual problems.

* cgroup_unload_subsys() was forgetting to free idr, call
  ->pre_destroy() and clear ->active.  As there currently is no
  modular controller which uses ->use_id, ->pre_destroy() or ->active,
  this doesn't cause any actual problems.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2012-11-19 08:13:37 -08:00
parent 648bb56d07
commit 02ae7486d0
1 changed files with 14 additions and 1 deletions
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15
kernel/cgroup.c
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@ -4420,9 +4420,10 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
if (ss->use_id) {
int ret = cgroup_init_idr(ss, css);
if (ret) {
dummytop->subsys[ss->subsys_id] = NULL;
ss->destroy(dummytop);
dummytop->subsys[ss->subsys_id] = NULL;
subsys[ss->subsys_id] = NULL;
list_del_init(&ss->sibling);
mutex_unlock(&cgroup_mutex);
return ret;
}
@ -4490,7 +4491,19 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
*/
BUG_ON(ss->root != &rootnode);
/* ->pre_destroy() should be called outside cgroup_mutex for now */
if (ss->pre_destroy)
ss->pre_destroy(dummytop);
mutex_lock(&cgroup_mutex);
ss->active = 0;
if (ss->use_id) {
idr_remove_all(&ss->idr);
idr_destroy(&ss->idr);
}
/* deassign the subsys_id */
subsys[ss->subsys_id] = NULL;